ABSTRACT: 0044

Effect of Fluoride on Ni-Ti and Cu-Ni-Ti Archwires- Invivo Study

A. RAMALINGAM, V. KAILASAM, S. PADHMANABAN, and A. CHITHARANJAN, Shri Ramachandra Dentl College, Chennai, India

Objectives:Evaluate effect of fluoride agents on mechanical properties of Ni-Ti and CopperNi-Ti archwires and their effects on physical property (surface topography) using SEM.

Materials & Methods:Thirty fixed appliance patients with 0.016x0.022” CuNiTi wires in upper arch and 0.016x0.022”NiTi wires in lower arch were randomly assigned to three groups:

Group I –Without fluoride application(control)

Group II-Subjected to fluoride rinse

Group III-Subjected to fluoride gel. After a month,wires subjected to three-point bend test(Instron machine) were loaded to 3.1mm deflection,unloaded to zero deflection at cross–head speed of 1mm/minute.Every 0.2mm deflection for loading and unloading were recorded and statistically analysed (one-way ANOVA,Tukey-HSD).One set of wires(upper and lower)randomly selected from each group were analysed to characterize surface topography.

Results: Comparison of mechanical properties of NiTi archwires after fluoride rinse and gel application:

Group	E (Loading) GPa	E (Unloading) GPa	YS (Loading) MPa	YS (Unloading) MPa
Control	54.78±7.66	32.90±3.71	667.14±64.96	291.06±102.79
Fluoride solution	50.65 ±9.87	30.12±6.88	655.98±177.25	266.78±93.52
Fluoride gel	53.27± 16.29	21.61±10.23	650.47±85.24	197.34±72.47
p value	0.735	0.006*	0.951	0.073

* Statistically significant

During unloading,modulus of elasticity(E) and yield strength (YS) of NiTi were reduced.

Comparison of mechanical properties of CuNiTi archwires after fluoride rinse and gel application:

Group	E (Loading) GPa	E (Unloading) GPa	YS (Loading) MPa	YS (Unloading) MPa
Control	47.76±14.05	12.40±8.31	374.84±98.06	168.66±50.06
Fluoride solution	45.35±18.99	9.59±3.29	350.61±142.72	155.15±100.67
Fluoride gel	44.36± 6.83	10.26±4.79	318.62±92.01	157.18±70.65
p value	0.860	0.542	0.545	0.809

Results showed no significant reduction in mechanical properties of CuNiTi archwires in controls group,rinse and gel groups during loading and unloading with p< 0.05.SEM revealed more white spots on NiTi wires and pitting corrosion in CuNiTi wires.Surface degradation was more in CuNiTi group.

Conclusion:The use of topical fluoride agents could adversely affect the unloading properties of NiTi wires and delay orthodontic treatment.

Seq #12 - Wires for Rotary Instruments, Orthodontic Wires, and Bonding
2:15 PM-3:45 PM, Wednesday, July 2, 2008
Metro Toronto Convention Centre Room 803A

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